Your joking right?
First off, the sensor isn't any different than any other 18mp body.. Same tech, same processor.
What you are seeing is a difference of metering and/or exposure of the scene. The SL1 clearly shows to be brighter (by compensation, meter, or gain) than the 7D or D7100. The other two bodies will show less noticeable noise in the shadows of those shots because the shadows are darker...duh. The exposure of the scene needed to be balanced across each body if they are going to 'compare' the results.
Secondly, why the hell is this guy comparing the cheapest Canon 18mp body ($799 with 18-55IS/STM) with the highest-end crop bodies from Canon and Nikon??? Then expecting it to be some improvement over, or better performance than those models.. Really??? (*T3i was $799 body only when released)
Thirdly, why are you giving any validation to this guys review to begin with when they apparently do not know the impact under/over exposure has on shadow noise. This is some website that is supposedly teaching about 'photography' yet at the same time is giving advice about what camera you should consider an upgrade to when you already have last years model... Sorry, if anyone is 'needing' to upgrade their camera body every time each new model comes out you are not interested in photography, and certainly do not need to be worried about a microscopic difference between this/that model.
Purely from a tech-gadget perspective: No, this cheapest 18mp body is not an upgrade from Canon's most expensive 18mp body, nor is it a cost alternative to Nikon's most expensive APS-C body.. Shouldn't really be a surprise to anyone.
(@Robboesan) Nikon has had one (1) new sensor since the 2010 16mp D7000, and that is the 24mp that was only recently announced in a couple of bodies. Nikon is not introducing a new sensor because they are concerned with providing the public the best technology for digital photography. If Nikon did not feel they were under marketing pressure from consumers who are more interested in the social tag their equipment might provide, they would not have released a new sensor at all. The 16mp sensor in the D7000 and D5100 is far superior to the new 'film-grain' 24mp by a far margin, so without the marketing pressure of being a whole (2) megapixels behind Canon they would have milked the 16mp sensor for an eternity just like their APS-C 12mp sensor.
(Really, grain?.. Re-introducing a negative artifact of the film era as something beneficial is appalling. Grain is something digital photography moved beyond in the early years of the technology. Marketing high megapixel induced 'film-like grain' at ISO/400 just to sell high megapixel cameras is absurd.)